// Ported from Stefan Gustavson's java implementation
// http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
// Read Stefan's excellent paper for details on how this code works.
//
// Sean McCullough banksean@gmail.com
//
// Added 4D noise

/**
 * You can pass in a random number generator object if you like.
 * It is assumed to have a random() method.
 */
var SimplexNoise = function (r) {
  if (r == undefined) r = Math
  this.grad3 = [
    [1, 1, 0],
    [-1, 1, 0],
    [1, -1, 0],
    [-1, -1, 0],
    [1, 0, 1],
    [-1, 0, 1],
    [1, 0, -1],
    [-1, 0, -1],
    [0, 1, 1],
    [0, -1, 1],
    [0, 1, -1],
    [0, -1, -1],
  ]

  this.grad4 = [
    [0, 1, 1, 1],
    [0, 1, 1, -1],
    [0, 1, -1, 1],
    [0, 1, -1, -1],
    [0, -1, 1, 1],
    [0, -1, 1, -1],
    [0, -1, -1, 1],
    [0, -1, -1, -1],
    [1, 0, 1, 1],
    [1, 0, 1, -1],
    [1, 0, -1, 1],
    [1, 0, -1, -1],
    [-1, 0, 1, 1],
    [-1, 0, 1, -1],
    [-1, 0, -1, 1],
    [-1, 0, -1, -1],
    [1, 1, 0, 1],
    [1, 1, 0, -1],
    [1, -1, 0, 1],
    [1, -1, 0, -1],
    [-1, 1, 0, 1],
    [-1, 1, 0, -1],
    [-1, -1, 0, 1],
    [-1, -1, 0, -1],
    [1, 1, 1, 0],
    [1, 1, -1, 0],
    [1, -1, 1, 0],
    [1, -1, -1, 0],
    [-1, 1, 1, 0],
    [-1, 1, -1, 0],
    [-1, -1, 1, 0],
    [-1, -1, -1, 0],
  ]

  this.p = []

  for (var i = 0; i < 256; i++) {
    this.p[i] = Math.floor(r.random() * 256)
  }

  // To remove the need for index wrapping, double the permutation table length
  this.perm = []

  for (var i = 0; i < 512; i++) {
    this.perm[i] = this.p[i & 255]
  }

  // A lookup table to traverse the simplex around a given point in 4D.
  // Details can be found where this table is used, in the 4D noise method.
  this.simplex = [
    [0, 1, 2, 3],
    [0, 1, 3, 2],
    [0, 0, 0, 0],
    [0, 2, 3, 1],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [1, 2, 3, 0],
    [0, 2, 1, 3],
    [0, 0, 0, 0],
    [0, 3, 1, 2],
    [0, 3, 2, 1],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [1, 3, 2, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [1, 2, 0, 3],
    [0, 0, 0, 0],
    [1, 3, 0, 2],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [2, 3, 0, 1],
    [2, 3, 1, 0],
    [1, 0, 2, 3],
    [1, 0, 3, 2],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [2, 0, 3, 1],
    [0, 0, 0, 0],
    [2, 1, 3, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [2, 0, 1, 3],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [3, 0, 1, 2],
    [3, 0, 2, 1],
    [0, 0, 0, 0],
    [3, 1, 2, 0],
    [2, 1, 0, 3],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0],
    [3, 1, 0, 2],
    [0, 0, 0, 0],
    [3, 2, 0, 1],
    [3, 2, 1, 0],
  ]
}

SimplexNoise.prototype.dot = function (g, x, y) {
  return g[0] * x + g[1] * y
}

SimplexNoise.prototype.dot3 = function (g, x, y, z) {
  return g[0] * x + g[1] * y + g[2] * z
}

SimplexNoise.prototype.dot4 = function (g, x, y, z, w) {
  return g[0] * x + g[1] * y + g[2] * z + g[3] * w
}

SimplexNoise.prototype.noise = function (xin, yin) {
  var n0, n1, n2 // Noise contributions from the three corners
  // Skew the input space to determine which simplex cell we're in
  var F2 = 0.5 * (Math.sqrt(3.0) - 1.0)
  var s = (xin + yin) * F2 // Hairy factor for 2D
  var i = Math.floor(xin + s)
  var j = Math.floor(yin + s)
  var G2 = (3.0 - Math.sqrt(3.0)) / 6.0
  var t = (i + j) * G2
  var X0 = i - t // Unskew the cell origin back to (x,y) space
  var Y0 = j - t
  var x0 = xin - X0 // The x,y distances from the cell origin
  var y0 = yin - Y0
  // For the 2D case, the simplex shape is an equilateral triangle.
  // Determine which simplex we are in.
  var i1, j1 // Offsets for second (middle) corner of simplex in (i,j) coords
  if (x0 > y0) {
    i1 = 1
    j1 = 0

    // lower triangle, XY order: (0,0)->(1,0)->(1,1)
  } else {
    i1 = 0
    j1 = 1
  } // upper triangle, YX order: (0,0)->(0,1)->(1,1)

  // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
  // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
  // c = (3-sqrt(3))/6
  var x1 = x0 - i1 + G2 // Offsets for middle corner in (x,y) unskewed coords
  var y1 = y0 - j1 + G2
  var x2 = x0 - 1.0 + 2.0 * G2 // Offsets for last corner in (x,y) unskewed coords
  var y2 = y0 - 1.0 + 2.0 * G2
  // Work out the hashed gradient indices of the three simplex corners
  var ii = i & 255
  var jj = j & 255
  var gi0 = this.perm[ii + this.perm[jj]] % 12
  var gi1 = this.perm[ii + i1 + this.perm[jj + j1]] % 12
  var gi2 = this.perm[ii + 1 + this.perm[jj + 1]] % 12
  // Calculate the contribution from the three corners
  var t0 = 0.5 - x0 * x0 - y0 * y0
  if (t0 < 0) n0 = 0.0
  else {
    t0 *= t0
    n0 = t0 * t0 * this.dot(this.grad3[gi0], x0, y0) // (x,y) of grad3 used for 2D gradient
  }

  var t1 = 0.5 - x1 * x1 - y1 * y1
  if (t1 < 0) n1 = 0.0
  else {
    t1 *= t1
    n1 = t1 * t1 * this.dot(this.grad3[gi1], x1, y1)
  }

  var t2 = 0.5 - x2 * x2 - y2 * y2
  if (t2 < 0) n2 = 0.0
  else {
    t2 *= t2
    n2 = t2 * t2 * this.dot(this.grad3[gi2], x2, y2)
  }

  // Add contributions from each corner to get the final noise value.
  // The result is scaled to return values in the interval [-1,1].
  return 70.0 * (n0 + n1 + n2)
}

// 3D simplex noise
SimplexNoise.prototype.noise3d = function (xin, yin, zin) {
  var n0, n1, n2, n3 // Noise contributions from the four corners
  // Skew the input space to determine which simplex cell we're in
  var F3 = 1.0 / 3.0
  var s = (xin + yin + zin) * F3 // Very nice and simple skew factor for 3D
  var i = Math.floor(xin + s)
  var j = Math.floor(yin + s)
  var k = Math.floor(zin + s)
  var G3 = 1.0 / 6.0 // Very nice and simple unskew factor, too
  var t = (i + j + k) * G3
  var X0 = i - t // Unskew the cell origin back to (x,y,z) space
  var Y0 = j - t
  var Z0 = k - t
  var x0 = xin - X0 // The x,y,z distances from the cell origin
  var y0 = yin - Y0
  var z0 = zin - Z0
  // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
  // Determine which simplex we are in.
  var i1, j1, k1 // Offsets for second corner of simplex in (i,j,k) coords
  var i2, j2, k2 // Offsets for third corner of simplex in (i,j,k) coords
  if (x0 >= y0) {
    if (y0 >= z0) {
      i1 = 1
      j1 = 0
      k1 = 0
      i2 = 1
      j2 = 1
      k2 = 0

      // X Y Z order
    } else if (x0 >= z0) {
      i1 = 1
      j1 = 0
      k1 = 0
      i2 = 1
      j2 = 0
      k2 = 1

      // X Z Y order
    } else {
      i1 = 0
      j1 = 0
      k1 = 1
      i2 = 1
      j2 = 0
      k2 = 1
    } // Z X Y order
  } else {
    // x0<y0

    if (y0 < z0) {
      i1 = 0
      j1 = 0
      k1 = 1
      i2 = 0
      j2 = 1
      k2 = 1

      // Z Y X order
    } else if (x0 < z0) {
      i1 = 0
      j1 = 1
      k1 = 0
      i2 = 0
      j2 = 1
      k2 = 1

      // Y Z X order
    } else {
      i1 = 0
      j1 = 1
      k1 = 0
      i2 = 1
      j2 = 1
      k2 = 0
    } // Y X Z order
  }

  // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
  // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
  // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
  // c = 1/6.
  var x1 = x0 - i1 + G3 // Offsets for second corner in (x,y,z) coords
  var y1 = y0 - j1 + G3
  var z1 = z0 - k1 + G3
  var x2 = x0 - i2 + 2.0 * G3 // Offsets for third corner in (x,y,z) coords
  var y2 = y0 - j2 + 2.0 * G3
  var z2 = z0 - k2 + 2.0 * G3
  var x3 = x0 - 1.0 + 3.0 * G3 // Offsets for last corner in (x,y,z) coords
  var y3 = y0 - 1.0 + 3.0 * G3
  var z3 = z0 - 1.0 + 3.0 * G3
  // Work out the hashed gradient indices of the four simplex corners
  var ii = i & 255
  var jj = j & 255
  var kk = k & 255
  var gi0 = this.perm[ii + this.perm[jj + this.perm[kk]]] % 12
  var gi1 = this.perm[ii + i1 + this.perm[jj + j1 + this.perm[kk + k1]]] % 12
  var gi2 = this.perm[ii + i2 + this.perm[jj + j2 + this.perm[kk + k2]]] % 12
  var gi3 = this.perm[ii + 1 + this.perm[jj + 1 + this.perm[kk + 1]]] % 12
  // Calculate the contribution from the four corners
  var t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0
  if (t0 < 0) n0 = 0.0
  else {
    t0 *= t0
    n0 = t0 * t0 * this.dot3(this.grad3[gi0], x0, y0, z0)
  }

  var t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1
  if (t1 < 0) n1 = 0.0
  else {
    t1 *= t1
    n1 = t1 * t1 * this.dot3(this.grad3[gi1], x1, y1, z1)
  }

  var t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2
  if (t2 < 0) n2 = 0.0
  else {
    t2 *= t2
    n2 = t2 * t2 * this.dot3(this.grad3[gi2], x2, y2, z2)
  }

  var t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3
  if (t3 < 0) n3 = 0.0
  else {
    t3 *= t3
    n3 = t3 * t3 * this.dot3(this.grad3[gi3], x3, y3, z3)
  }

  // Add contributions from each corner to get the final noise value.
  // The result is scaled to stay just inside [-1,1]
  return 32.0 * (n0 + n1 + n2 + n3)
}

// 4D simplex noise
SimplexNoise.prototype.noise4d = function (x, y, z, w) {
  // For faster and easier lookups
  var grad4 = this.grad4
  var simplex = this.simplex
  var perm = this.perm

  // The skewing and unskewing factors are hairy again for the 4D case
  var F4 = (Math.sqrt(5.0) - 1.0) / 4.0
  var G4 = (5.0 - Math.sqrt(5.0)) / 20.0
  var n0, n1, n2, n3, n4 // Noise contributions from the five corners
  // Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in
  var s = (x + y + z + w) * F4 // Factor for 4D skewing
  var i = Math.floor(x + s)
  var j = Math.floor(y + s)
  var k = Math.floor(z + s)
  var l = Math.floor(w + s)
  var t = (i + j + k + l) * G4 // Factor for 4D unskewing
  var X0 = i - t // Unskew the cell origin back to (x,y,z,w) space
  var Y0 = j - t
  var Z0 = k - t
  var W0 = l - t
  var x0 = x - X0 // The x,y,z,w distances from the cell origin
  var y0 = y - Y0
  var z0 = z - Z0
  var w0 = w - W0

  // For the 4D case, the simplex is a 4D shape I won't even try to describe.
  // To find out which of the 24 possible simplices we're in, we need to
  // determine the magnitude ordering of x0, y0, z0 and w0.
  // The method below is a good way of finding the ordering of x,y,z,w and
  // then find the correct traversal order for the simplex we’re in.
  // First, six pair-wise comparisons are performed between each possible pair
  // of the four coordinates, and the results are used to add up binary bits
  // for an integer index.
  var c1 = x0 > y0 ? 32 : 0
  var c2 = x0 > z0 ? 16 : 0
  var c3 = y0 > z0 ? 8 : 0
  var c4 = x0 > w0 ? 4 : 0
  var c5 = y0 > w0 ? 2 : 0
  var c6 = z0 > w0 ? 1 : 0
  var c = c1 + c2 + c3 + c4 + c5 + c6
  var i1, j1, k1, l1 // The integer offsets for the second simplex corner
  var i2, j2, k2, l2 // The integer offsets for the third simplex corner
  var i3, j3, k3, l3 // The integer offsets for the fourth simplex corner
  // simplex[c] is a 4-vector with the numbers 0, 1, 2 and 3 in some order.
  // Many values of c will never occur, since e.g. x>y>z>w makes x<z, y<w and x<w
  // impossible. Only the 24 indices which have non-zero entries make any sense.
  // We use a thresholding to set the coordinates in turn from the largest magnitude.
  // The number 3 in the "simplex" array is at the position of the largest coordinate.
  i1 = simplex[c][0] >= 3 ? 1 : 0
  j1 = simplex[c][1] >= 3 ? 1 : 0
  k1 = simplex[c][2] >= 3 ? 1 : 0
  l1 = simplex[c][3] >= 3 ? 1 : 0
  // The number 2 in the "simplex" array is at the second largest coordinate.
  i2 = simplex[c][0] >= 2 ? 1 : 0
  j2 = simplex[c][1] >= 2 ? 1 : 0
  k2 = simplex[c][2] >= 2 ? 1 : 0
  l2 = simplex[c][3] >= 2 ? 1 : 0
  // The number 1 in the "simplex" array is at the second smallest coordinate.
  i3 = simplex[c][0] >= 1 ? 1 : 0
  j3 = simplex[c][1] >= 1 ? 1 : 0
  k3 = simplex[c][2] >= 1 ? 1 : 0
  l3 = simplex[c][3] >= 1 ? 1 : 0
  // The fifth corner has all coordinate offsets = 1, so no need to look that up.
  var x1 = x0 - i1 + G4 // Offsets for second corner in (x,y,z,w) coords
  var y1 = y0 - j1 + G4
  var z1 = z0 - k1 + G4
  var w1 = w0 - l1 + G4
  var x2 = x0 - i2 + 2.0 * G4 // Offsets for third corner in (x,y,z,w) coords
  var y2 = y0 - j2 + 2.0 * G4
  var z2 = z0 - k2 + 2.0 * G4
  var w2 = w0 - l2 + 2.0 * G4
  var x3 = x0 - i3 + 3.0 * G4 // Offsets for fourth corner in (x,y,z,w) coords
  var y3 = y0 - j3 + 3.0 * G4
  var z3 = z0 - k3 + 3.0 * G4
  var w3 = w0 - l3 + 3.0 * G4
  var x4 = x0 - 1.0 + 4.0 * G4 // Offsets for last corner in (x,y,z,w) coords
  var y4 = y0 - 1.0 + 4.0 * G4
  var z4 = z0 - 1.0 + 4.0 * G4
  var w4 = w0 - 1.0 + 4.0 * G4
  // Work out the hashed gradient indices of the five simplex corners
  var ii = i & 255
  var jj = j & 255
  var kk = k & 255
  var ll = l & 255
  var gi0 = perm[ii + perm[jj + perm[kk + perm[ll]]]] % 32
  var gi1 = perm[ii + i1 + perm[jj + j1 + perm[kk + k1 + perm[ll + l1]]]] % 32
  var gi2 = perm[ii + i2 + perm[jj + j2 + perm[kk + k2 + perm[ll + l2]]]] % 32
  var gi3 = perm[ii + i3 + perm[jj + j3 + perm[kk + k3 + perm[ll + l3]]]] % 32
  var gi4 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1 + perm[ll + 1]]]] % 32
  // Calculate the contribution from the five corners
  var t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0 - w0 * w0
  if (t0 < 0) n0 = 0.0
  else {
    t0 *= t0
    n0 = t0 * t0 * this.dot4(grad4[gi0], x0, y0, z0, w0)
  }

  var t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1 - w1 * w1
  if (t1 < 0) n1 = 0.0
  else {
    t1 *= t1
    n1 = t1 * t1 * this.dot4(grad4[gi1], x1, y1, z1, w1)
  }

  var t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2 - w2 * w2
  if (t2 < 0) n2 = 0.0
  else {
    t2 *= t2
    n2 = t2 * t2 * this.dot4(grad4[gi2], x2, y2, z2, w2)
  }

  var t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3 - w3 * w3
  if (t3 < 0) n3 = 0.0
  else {
    t3 *= t3
    n3 = t3 * t3 * this.dot4(grad4[gi3], x3, y3, z3, w3)
  }

  var t4 = 0.6 - x4 * x4 - y4 * y4 - z4 * z4 - w4 * w4
  if (t4 < 0) n4 = 0.0
  else {
    t4 *= t4
    n4 = t4 * t4 * this.dot4(grad4[gi4], x4, y4, z4, w4)
  }

  // Sum up and scale the result to cover the range [-1,1]
  return 27.0 * (n0 + n1 + n2 + n3 + n4)
}

export {SimplexNoise}
